No idea what's going on here, but sometime within the last week or so Skype on my iPhone SE has stopped making any text-related sounds. Phone calls are fine including ringing and speaking/listening, but notifications will not make a sound. iOS notifications for Skype are enabled, Notifications within Skype itself are enabled, and I am in "online" mode (not Do Not Disturb). I have rebooted my phone, quit & relaunched Skype, etc. Still no joy.
iPhone SE on iOS 10.3.1 (not willing to update to iOS11 so please don't even suggest it) Skype 188.8.131.52670 (and no way am I updating Skype. I made that mistake recently on another device and it was a disaster, plus it was working fine until very recently).
EDIT: And just like that, 20 minutes later... Skype started making noise again. I have absolutely NO idea why... I didn't do a thing.
EDIT 2: For whatever it's worth, Skype stopped making sounds again a couple days later. Then started again. It seems to basically just be random... sometimes it will make sounds, sometimes it won't. No rhyme or reason!